Method for using microelectromechanical systems to generate movement in a phacoemulsification handpiece

ABSTRACT

The present invention relates to a phacoemulsification handpiece, comprising a needle and a microelectromechanical system (MEMS) device, wherein the needle is coupled with the MEMS device. The phacoemulsification handpiece may further comprise a horn, wherein the horn is coupled with the needle and the MEMS device. The MEMS device is capable of generating movement of the needle in at least one direction, wherein at least one direction is selected from the group consisting of transversal, torsional, and longitudinal. The present invention also relates to a method of generating movement, comprising providing a phacoemulsification handpiece, wherein the handpiece comprises a needle and one or more MEMS devices; applying a voltage or current to the one or more MEMS devices, wherein the MEMS devices are coupled with the needle; and moving the needle in at least one direction. The present invention also relates to a vitrectomy cutter comprising one or more MEMS devices.

CLAIM OF PRIORITY

The present application claims priority under 35 U.S.C. §119(e) toprovisional application No. 61/311,695, filed on Mar. 8, 2010 under thesame title, which is incorporated herein by reference in its entirety.Full Paris Convention priority is hereby expressly reserved.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an ultrasound handpiece and inparticular, generating movement of a tip of the handpiece using microelectromechanical systems (MEMS).

BACKGROUND OF THE INVENTION

During a phacoemulsification (“phaco”) procedure, a needle of anultrasound handpiece is placed within the capsular bag of an eye toemulsify the cataractic lens. The emulsified lens is removed from theeye and an intraocular lens (“IOL”) is implanted. Ultrasound handpiecesare driven by piezoelectric crystals or magnetostrictive drivers. Energyis applied to the piezoelectric crystals to vibrate the crystals togenerate ultrasound energy, which is then transmitted through the needleof the handpiece into the cataractic lens. There are several theories asto how the cataractic lens is emulsified. One school of thought is thatthe ultrasound vibration causes cavitation, which in turn emulsifies thelens. Another school of thought is that the lens is emulsified by meremechanical breakdown. Also, another school of thought is that it is acombination of cavitation and mechanical breakdown that emulsifies thecataractic lens. Despite these theories, there are several limitationplaced on ultrasound handpieces when employing piezoelectric crystals.First, before each use the handpiece must be tuned, thereby lengtheningthe time of the procedure. Second, handpieces comprising piezoelectriccrystals generate significant heat during use that may cause tissuedamage. Third, the crystals add a significant amount of weight to thehandpieces making them heavy and cumbersome to use and can cause fatiguefor the doctors using such handpieces.

Based upon the foregoing, it would be advantageous to have a handpiecethat is lighter, does not require tuning prior to use, and does notgenerate tissue damaging heat.

SUMMARY OF THE INVENTION

The present invention relates to a phaco handpiece, comprising a needleand a MEMS device, wherein the needle is coupled with the MEMS device.The phaco handpiece may further comprise a horn, wherein the horn iscoupled with the needle and the MEMS device. The MEMS device is capableof generating movement of the needle in at least one direction, whereinat least one direction is selected from the group consisting oftransversal, torsional, and longitudinal along a longitudinal axis ofthe needle. The phaco handpiece may further comprise a pad and alinkage, wherein the pad is coupled with the MEMS device via the linkageand the pad is coupled with the needle. The pad may be coupled with theneedle via a linkage. The MEMS device may also be coupled with an outersurface of the needle.

The present invention also pertains to a method of generating movement,comprising providing a phaco handpiece, wherein the handpiece comprisesa needle and one or more MEMS devices; applying a voltage or current tothe one or more MEMS devices, wherein the MEMS devices are coupled withthe needle; and moving the needle in at least one direction. The atleast one direction may be selected from the group consisting oftransversal, torsional, and longitudinal along a longitudinal axis ofthe needle.

The present invention also pertains to a vitrectomy cutter, comprising aneedle body having one or more ports; a blade, wherein the blade islocated within the needle body and capable of passing over the one ormore ports; and a microelectromechanical system device, wherein themicroelectromechanical device is coupled with the blade; wherein themicroelectromechanical system device is capable of oscillating theblade.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is best understood with reference to the followingdetailed description of the invention and the drawings in which:

FIG. 1 is a cross-sectional view of an ultrasound phaco handpiece;

FIG. 2 is a plan view of an embodiment of a MEMS system;

FIG. 3 is a plan view of an embodiment of a MEMS system;

FIG. 4 is a bottom view of an embodiment of a MEMS system;

FIG. 5 is a side view of an embodiment of a MEMS system;

FIG. 6 is a plan view of an embodiment of a MEMS system;

FIG. 7 is a plan view of a vitrectomy cutter; and

FIG. 8 is a plan view of an embodiment of a MEMS system.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to embodiments of the invention,examples of which are illustrated in the accompanying drawings. Whilethe invention will be described in conjunction with the embodiments, itwill be understood that they are not intended to limit the invention tothose embodiments. On the contrary, the invention is intended to coveralternatives, modifications, and equivalents, which may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

In FIG. 1 a cross-section along the longitudinal axis of a portion of anultrasound phaco handpiece 100 known in the art is shown. Generally,handpiece 100 includes a needle 110, defining a lumen that isoperatively coupled with an aspiration pump (not shown), forming anaspiration line 114. The proximal end of needle 110 is coupled with horn150, which has its proximal end coupled with a set of piezoelectriccrystals 180, shown as three rings. Horn 150, crystals 180, and aproximal portion of the needle 110 are enclosed within handpiece casing170 having an irrigation port coupled with an irrigation line 190defining an irrigation pathway 195. Irrigation line 190 is coupled withan irrigation source (not shown). Horn 150 is typically an integratedmetal, such as titanium, structure and often includes a rubber O ring160 around the mid-section, just before horn 150 tapers to fit withneedle 110 at the distal end of horn 150. O ring 160 snugly fits betweenhorn 150 and casing 170. O ring 160 seals the proximal portion of horn150 from irrigation pathway 195. Thus, there is a channel of air definedbetween horn 150 and the casing 170. Descriptions of handpieces known inthe art are provided in U.S. Pat. No. 6,852,092 (Kadziauskas, et al.)and U.S. Pat. No. 5,843,109 (Mehta, et al.), which are herebyincorporated by reference in their entirety.

In preparation for operation, sleeve 120 is typically added to thedistal end of handpiece 100, covering the proximal portion of the needle110 (thus, exposing the distal tip of the needle), and the distal end ofirrigation pathway 195, thereby extending pathway 195 and defining anirrigation port 122 just before the distal tip of needle 110. Needle 110and a portion of sleeve 120 are then inserted through the cornea of theeye to reach the cataractic lens.

During operation, irrigation path 195, the eye's chamber and aspirationline 114 form a fluidic circuit, where irrigation fluid enters the eye'schamber via irrigation path 195, and is then aspirated throughaspiration line 114 along with other materials that the surgeon desiresto aspirate out, such as the cataractic lens. If, however, thematerials, such as the cataractic lens, are too hard and massive to beaspirated through the aspiration line 114, then the distal end of theneedle 110 is ultrasonically vibrated and applied to the material to beemulsified into a size and state that can be successfully aspirated.

Needle 110 is ultrasonically vibrated by applying electric power to thepiezoelectric crystals 180, which in turn, cause horn 150 toultrasonically vibrate and/or amplify the movement, which in turn,ultrasonically vibrates the needle 110. The electric power is defined bya number of parameters, such as signal frequency and amplitude, and ifthe power is applied in pulses, then the parameters can further includepulse width, shape, size, duty cycle, amplitude, and so on. Theseparameters are controlled by a control unit. An example of controllingsuch parameters is described in U.S. Pat. No. 7,169,123 to Kadziauskas,et al., which is hereby incorporated by reference in its entirety.

Vibration of needle 110 and horn 150 of handpiece 100 generatessignificant heat at the tip of the needle, which may damage tissue nearthe needle. This significant limitation is overcome by the presentinvention.

The present invention relates to using one or more MEMS devices togenerate movement of a needle of a handpiece. MEMS devices integratemechanical and electrical structures, sensors, and/or actuators on asilicon substrate using microfabrication. The combination of componentsallows a system to gather and process information, decide on a course ofaction, and control the surrounding environment. The benefits of such adevice include increased affordability, functionality, and performanceof products. MEMS work by sensors that measure mechanical, thermal,biological, chemical, magnetic, and/or optical signals from theenvironment. The microelectronic integrated circuits act as the “brains”of the system (the decision-making part of the system), by processingthe information from the sensors; and the actuators help the systemrespond by moving, positioning, pumping, filtering, or somehowcontrolling the surrounding environment to achieve its purpose.

MEMS devices have a characteristic length between 1 micron and 1 mm.MEMS: Design and Fabrication, edited by Mohamed Gad-el-Hak, 2^(nd)Edition, November 2005, which is hereby incorporated by reference in itsentirety. There are different varieties of MEMS devices, includingmicrosensors, micromotors, and microgears. Id. Current manufacturingtechniques for MEMS devices include surface silicon micromachining(depositing thin films on the surface); bulk silicon micromachining(forming mechanical structures in the silicon substrates—etching throughthe wafer); lithography, eletrodeposition, and plastic molding; andelectrodischarge machining. Id.

According to an embodiment, using one or more MEMS devices, a needle ofa handpiece can be oscillated to achieve similar movement of a needle ofan ultrasound handpiece. Traditional deposition and lithography used inmicrochip design today can be applied to create a microchip attached toa needle of a handpiece that vibrates the needle in any desireddirection, including, but not limited to, transversal (side-to-side),torsional, and longitudinal. In traditional deposition and lithographypractices two dissimilar materials are used, commonly referred to asdopants. Dopants are deposited onto a wafer using a variety oftechniques well known in the art. The dopants either have a positive ora negative charge; and the dopants are separated by a channel. Applyinga voltage or current to one of the doped sides causes the other side tobe attracted to the side where the current is applied. By removing thevoltage or current from the same side causes the sides to move away.Repeating this application of voltage or current creates motion. Inaddition to electrostatic attraction and repulsion, other forms ofgenerating force or movement using MEMS may be employed with the presentinvention, including but not limited to thermal and magnetic actuation.

The present invention also solves many problems associated withultrasound phaco handpieces. First, using one or more MEMS devices toactuate the needle of a handpiece reduces manufacturing time and costs.These reductions also make it possible to manufacture a single usedisposable handpieces that provide additional safety to the patient.Disposable handpieces may also reduce the amount of metal used with thehandpiece. Second, using one or more MEMS devices enables finer controlof the movement of the distal end of the needle, which promotes safercataractic lens removal. Finer control allows for a safer procedure bypreventing damage to tissue, including but not limited to tissuesurrounding the incision, the capsular bag, and other structures of theeye that may be exposed to the needle of the handpiece. With MEMS,movement of the distal end of the needle is always a known quantitybased on manufacturing processes. Without being limited to a theory, useof one or more MEMS devices coupled with a horn and/or a needle maycause the tip of the needle to oscillate and emulsify the lens bymechanical break down of the cataractic lens, e.g. a jackhammer. In anembodiment, multiple MEMS devices may be coupled with a horn and/orneedle to cause the tip of the needle to move in a single directionand/or multiple directions. In an embodiment, 5 to 6 MEMS devices may beused for movement in a single direction or in multiple directions. EachMEMS device may provide any desired tip excursion, including but notlimited to 1 mm to 2 mm.

MEMS devices of the present invention differ from standard ultrasonichandpieces in many ways, including the different phase angles andfrequencies are removed and replaced with voltage and current forcontrolling velocity and direction.

FIG. 2 illustrates an embodiment of the present invention. MEMS system200 includes MEMS device 220 and horn 250. MEMS device 220 comprisesdopant side 240 and dopant side 230. Dopant side 240 or dopant side 230may be positive or negative as long as one side is positive and theother is negative. Channel 225 is located between dopant side 240 anddopant side 230. The shape and/or size of channel 225, dopant side 230,and/or dopant side 240 may be changed to create different directions ofmovement.

FIG. 3 illustrates another embodiment of the present invention. In FIG.3, MEMS system 300 comprises horn 350 and MEMS devices 320, wherein horn350 is capable of being moved in at least two directions—transversaldirection 380 and longitudinal direction 370. The movement of horn 350causes a needle coupled with horn 350 to move in the same directions ashorn 350. MEMS device 320 may be coupled with horn 350 via linkages 315.Each MEMS device 320 may be activated at the same time or at differenttimes to achieve a desired movement of horn 350 and a needle coupledwith horn 350.

FIG. 4 illustrates another embodiment of the present invention.Specifically, FIG. 4 shows MEMS system 400. MEMS system 400 includesMEMS device 420 and horn 450. When MEMS devices 420 are activated, horn450 is rotated along its longitudinal axis as shown by rotationaldirection 490. MEMS devices 420 may be coupled with horn 450 vialinkages 415. MEMS devices 420 are capable of moving in directions 410and 430. Movement of MEMS devices 420 in a normal direction to thelongitudinal axis of horn 450 causes horn 450 to move in rotationaldirection 490.

FIG. 5 illustrates another embodiment where MEMS devices 520 of MEMSsystem 500 are coupled with horn 550 via linkages 515 on the outersurface 530 of horn 550. One or more MEMS devices 520 may be coupledwith outer surface 530 of horn 550. MEMS devices 520 may also be coupledwith born 550 via pads 505.

FIG. 6 illustrates another embodiment where MEMS system 600 comprisesmultiple MEMS devices 620, multiple pads 630, and multiple linkages 615.Horn 650 may be coupled with multiple MEMS devices 620 to generatemovement in multiple directions. As illustrated in FIG. 6, three MEMSdevices 620 are coupled with horn 650 via linkages 615 and pad 630.These three MEMS devices 620 are capable of generating movement of horn650 in longitudinal direction 640 (along a longitudinal axis of horn650). One MEMS device 620 may be coupled with horn 650 via linkages 615and pad 630. This MEMS device 620 is capable of generating movement ofhorn 650 in transverse direction 660 (perpendicular to a longitudinalaxis of horn 650). Linkages 615 may be coupled with an outer surface orend of horn 650. Linkages 615 may also be coupled with a surface of pads630. Linkages 615 may be of any shape or size. Pads 630 may also be ofany shape or size to accommodate the use of one or more MEMS devices620.

The linkages (315, 415, and 515) may be of any size or shape to enablecoupling of one or more MEMS devices (220, 320, 420, and 520) with ahorn (150, 250, 350, 450, and 550) and/or a needle. The linkages maycouple one or more MEMS device with one or more pads (505), a needle,and/or horn by any orientation and on any location of the MEMS device,pads, and/or horn in order to achieve the desired directional movement,amount of movement, and design of the handpiece. The linkages may alsobe coupled directly with an outer surface of a needle or a horn. Thelinkage may be of any material known in the art, including but notlimited to all ferrous and nonferrous metals.

In an embodiment, an asymmetric MEMS unit may be used. A single MEMSdevice may generate all of the movement required, including in anasymmetric fashion by asymmetrical coupling one or more linkages to thehorn and/or needle. With one pulse through the MEMS device an expansionand contraction movement will happen. The amount of force may beincreased or decreased depending upon the number of MEMS devices usedfor a particular directional movement.

According to another embodiment, the MEMS devices may also be used witha vitrectomy cutter. An example of a vitrectomy cutter is illustrated inU.S. Pat. No. 6,575,990 (Wang, et al.), which is hereby incorporated byreference in its entirety. Current vitrectomy cutters rely on air supplyto generate the movement of the cutting blade to cut the vitreous. Byusing one or more MEMS devices to actuate the movement of the cuttingblade, the problems associated with currently used vitrectomy cuttersmay be reduced, such as, but not limited to adjusting the air pressuredepending upon the altitude at which the surgery is performed. Moreover,eliminating the air supply would make the machines more compact andportable, thereby reducing the overall cost of the machines.

In FIG. 7 a vitrectomy cutter known in the art is illustrated.Vitrectomy cutter 700 includes handle 710 coupled with needle body 720.Needle body 720 comprises one or more ports 730. Housed within needlebody 720 is one or more blades 810 (see FIG. 8) that may pass over theone or more ports 730 of needle body 720, such that any vitreous thatenters port 730 may be cut by the one or more blades 810. The one ormore blades act as a guillotine.

In FIG. 8, a MEMS device system of the present invention is illustrated.MEMS device system 800 includes MEMS device 820 and blade 810. MEMSdevice system 800 may be housed within needle body 720 and/or handle710. One or more MEMS devices 820 may be coupled with one or more blades810. Activation of one or more MEMS devices 820 causes movement of blade810 in direction 830 causing blade 810 to act as a guillotine to cut thevitreous. The MEMS devices may be coupled with the one or more bladesdirectly or via a pad/linkage system as described herein. As shown inFIG. 8, blade 810 is coupled with MEMS device 820 via linkage 815. Asdiscussed above, the linkages (e.g. 815) may be of any size or shape toenable coupling of one or more MEMS devices (820) with blade 810 and/orone or more pads.

MEMS devices of the present invention may be made of any material knownin the art, including but not limited to polycrystalline silicon. Thesize of the MEMS devices may be of any size and shape that provides thenecessary movement of the needle and fits within a standard sizedhandpiece, handle, and/or needle body.

As described herein, one or more MEMS devices may be coupled with aneedle instead of a horn. In some embodiments, a needle and a horn maybe one unit and referred to as a horn or a needle.

The present invention provides more reliability and is more costeffective due to the manufacturing process, e.g. cmos manufacturing,resulting in less failures and returns. In an embodiment, aphacoemulsification handpiece has one or more MEMS devices and isdisposable. A disposable handpiece would reduce the need forsterilization and minimize the risk of cross-contamination.

All references cited herein are hereby incorporated by reference intheir entirety including any references cited therein.

Although the present invention has been described in terms of specificembodiments, changes and modifications can be carried out withoutdeparting from the scope of the invention which is intended to belimited only by the scope of the claims.

1. A phacoemulsification handpiece, comprising: a needle; and multiplemicroelectromechanical system devices, wherein the needle is coupledwith the microelectromechanical system devices.
 2. Thephacoemulsification handpiece of claim 1, further comprising a horn,wherein in the horn is coupled with the needle and themicroelectromechanical system devices.
 3. The phacoemulsificationhandpiece of claim 1, wherein the microelectromechanical system devicesare capable of generating movement of the needle in at least onedirection.
 4. The phacoemulsification handpiece of claim 3, wherein atleast one direction is selected from the group consisting oftransversal, torsional, and longitudinal along a longitudinal axis ofthe needle.
 5. The phacoemulsification handpiece of claim 1, furthercomprising a pad and a linkage, wherein the pad is coupled with themicroelectromechanical system devices via the linkage and the pad iscoupled with the needle.
 6. The phacoemulsification handpiece of claim5, wherein the pad is coupled with the needle via a linkage.
 7. Thephacoemulsification handpiece of claim 1, wherein themicroelectromechanical system devices are coupled with an outer surfaceof the needle.
 8. A method of generating movement, comprising: providinga phacoemulsification handpiece, wherein the handpiece comprises aneedle and one or more microelectromechanical system devices; applying avoltage or current to the one or more microelectromechanical systemdevices, wherein the microelectromechanical system devices are coupledwith the needle; and moving the needle in at least one direction.
 9. Themethod of claim 8, wherein the at least one direction is selected fromthe group consisting of transversal, torsional, and longitudinal along alongitudinal axis of the needle.
 10. A vitrectomy cutter, comprising: aneedle body having one or more ports; a blade, wherein the blade islocated within the needle body and capable of passing over the one ormore ports; and a microelectromechanical system device, wherein themicroelectromechanical device is coupled with the blade; wherein themicroelectromechanical system device is capable of oscillating theblade.
 11. The vitrectomy cutter of claim 10, wherein themicroelectromechanical system is coupled with the blade via a linkage.